1. Field of the Invention
The present invention relates generally to conveyor systems and, more particularly, to a closed loop conveyor system including pulleys having annular grooves and a conveyor belt including cleats arranged in longitudinal rows for mating with the pulley grooves to provide improved frictional drive contact and belt-to-pulley alignment and to reduce cross tensions in the belt.
2. Description of the Prior Art
Heretofore, endless belts and pulleys used in closed loop heavy load conveyor systems have usually had smooth interior pulley engaging surfaces and the pulleys used to drive these belts have had smooth driving surfaces which are crowned to keep the belt centered over the pulley. Because of the smooth surfaces, the entire width of the interior belt surface frictionally contacts the pulley surface as the belt passes over the pulley. In cases where off-centered loads are carried by the belt, or where the belts are side-loaded, it is not unusual to have cross tensions build up in the belt which are substantial enough to overcome the centering action of the pulley crowns, causing the belt to be thrown off of the pulleys.
In those applications where the conveyor is used to carry loads up an incline from one level to another, slippage between the belt and the driving pulley often presents a problem. This has usually been overcome by increasing the belt tension and/or increasing the diameter of the drive pulley. However, these solutions frequently reduce the useful life of the belt and cause increased bearing wear in the pulleys. This is a particularly severe consequence in the case of larger diameter pulleys which usually cost substantially more to manufacture than pulleys of a smaller diameter. It should also be noted that these solutions frequently have an adverse effect on the effectiveness of the prior art belt centering techniques mentioned above.